Means for mounting printing plates



P. H. NEWMAN 3,

MEANS FOR mouu'rmc PRINTING PLATES Filed Aug. 5, 1965 Oct. 13, 1964 2 4 2 yy 17 17 x 7: W

United States Patent M 3,152,544 MEANS FUR MOUNTING PRINTING PLATES Pete Henry Newman, Kingston, England, assignor to Thomas De La Rue Engineering Limited, London, England, a corporation of the United Kingdom Filed Aug. 5, 1963, Ser. No. 299,706 Claims priority, application Great Britain, Aug. 8, 1962, 30,383/62 5 Claims. (Cl. 101-4151) This invention relates to cylindrical printing surfaces for use in intaglio printing machines and in particular for the web printing of security documents, banknotes, stamps or the like. W'nen producing, for example, stamps in endless form, the essential requirements are to provide an intagliated printing cylinder having an unbroken printing surface and to ensure that the circumference can accommodate a whole number of exactly spaced integers each equal to the vertical or horizontal pitch of a stamp.

The traditional method of producing such a printing surface comprises a rolling transfer process to produce a multiple intaglio matrix on the surface of a solid printing cylinder from a suitably prepared cameo-negative. Such a cylinder is necessarily very expensive. When using this traditional method, where a plurality of cylinders is needed, it is necessary for each cylinder to be transferred by the rolling-in method, step by step, which requires skill of the highest order.

A second known method comprises mounting a detachable printing surface around the periphery of a solid cylinder. A known form of construction comprises a plurality of arcuately formed printing plates attached to the cylinder by means of a system of internal claws or clamping bolts. In this arrangement the printing segments must have suificient thickness to accommodate suitable pockets or cavities capable of engaging with the attachment means. In this form of construction the joins in the plate surface are arranged to coincide with blank areas between the units forming the matrix and the essential conditions of unbroken eifective printing sur-- face and pitch are thus satisfied.

A preferable and more convenient suggested method of forming a printing surfaces comprises mounting a relatively thin plate, having a thickness of approximately .040" for example, on to the surface of a cylinder. Such a plate may be readily produced by electro-deposition from a metal or plastic master plate, which has the advantage of permitting a large number of plates to be 7 made automatically from the one master. It is, however, difficult and costly to make plates by the electrodeposition that are thick enough to accommodate internal clamping means. Considerable difiiculties are presented in a satisfactory method of securing and tensioning a thin plate on to a cylinder without including undesirable zones of ineffective printing surface. In the instance of web printing, and of postage stamp printing in particular, the maximum tolerable gap of effective printing surface may be as little as .060" for example which is arranged in the perforation zone between rows of stamps.

It is the object of the present invention to provide an improved method of mounting on to the circumference of a printing cylinder a thin printing surface that may be readily detached and adjusted.

According to the present invention a printing cylinder assembly for use in an intaglio printing machine comprises a transversely grooved cylinder, a plurality of thin segmental intagliated printing plates having a thickness of less than 0.125", clamping bars for mounting said printing plates on the cylinder, said clamping bars being adapted to be secured within the transverse grooves of the cylinder and axially slidable wedge members adapted 3,152,544 Patented Oct. 13, 1964 to engage between each pair of adjacent clamping bars and the cylinder or cylinder assembly whereby the clamping bars are affixed to the underside of each end of the said plates.

Preferably the clamping bars are electrically brazed in the printing plates by the resistance or induction heating processes. Preferably before brazing, the working surfaces of the plates, in the vicinity of the zones to be heated, are first temporarily copper-plated to provide protection against damage.

The transverse clamping bars preferably are also provided with adjustment means to engage the respective transverse grooves in the cylinder to enable the plates to be adjusted, tensioned and aligned.

The means for securing the bars may comprise axially slidable wedge members adapted to engage between each pair of adjacent clamping bars and the cylinder or cylinder assembly.

Preferably the dimensions of the clamping bars and the cylinder grooves are so arranged in any given case to ensure that the effective printing area of the plates is supported; the gaps between contiguous ends of adjacent clamping bars and between the clamping bars and the cylinder are thus arranged to occur below gaps between printing plates or below plate areas which have no effective printing surface e.g. the transverse gaps or gutters between adjacent images on multiple-image plates.

An example of the invention is now described with reference to the accompanying drawings in which FIG- URE 1 is a diagrammatic side elevation of one end of a printing plate; FIGURE 2 is a fragmentary cross-section of a printing cylinder, showing the ends of two adjacent printing plates in position together with the associated attachment and adjustment means; FIGURE 3 is a side elevation of an I-shaped locking bar, shown in section in FIGURE 2; FIGURE 4 is a longitudinal section of a sole plate, shown in transverse section in FIGURE 2; and FIGURE 5 is a longitudinal section of a clamping slide shown in transverse section in FIGURE 2. Each of FIGURES 3-5 is on a reduced scale compared to FIG- URES 1 and 2.

Referring first to FIGURE 1, a portion of an intaglio printing surface is shown by numeral 1 and represents the end of one of a plurality of segmental units forming the printing surface of the printing cylinder. The plate 1 comprises a grown nickel or composite plate having a thickness of approximately .050 and which incorporates an engraved or intagliated pattern on its upper working face. A transverse clamping bar 2 comprises a bar of mild steel or bronze alloy of approximately rectangular section, that is brazed on the underside of the plate. The upper surface 3 of the bar is curved to conform with the radius of the printing cylinder, on to which the plate is to be mounted, and one face of the bar 2 is grooved at 4 to receive a locking member to be described later. The opposite face 5 of the bar is tapered slightly to facilitate assembly on the cylinder. Tapped holes 6 are provided in the bar at suitable intervals to receive grub screws for adjustment purposes.

As is to be seen, x represents the overall length of one unit of the design of the matrix and y the distance between the units. To maintain a continuity of pitch with an adjacent plate segment it will be necessary to provide a terminate zone equal to y/ 2. In actual practice, it is desirable to reduce this very slightly to permit adjustment of the plate segments; therefore, this zone is shown as y/ 2 in the diagram. For satisfactory printing by the intaglio process, it is necessary to employ a high contacting pressure between the impression cylinder and the printing plate; it is thus essential that the relatively thin plate is fully supported in the effective printing areas.

For this reason it follows that the length of the surface 3 of the clamping bar must be related to the pitch of the printing matrix and arranged so that the extremity of the bar is situated below the y zone of the plate as shown.

The brazing is carried out by inserting an interposed foil of brazing material and a suitable flux between the clamping bar and the plate. Heat may be applied by means of the induction or resistance processes. In the latter case, a protective strip is placed above the plate and the assembly passed through a wheel type seam welder for example. Other types of brazing materials may be used including various grades of hard or soft solders providing they possess sufficient strength.

It is preferable to protect the working surface of the nickel plate against damage or deterioration during the heating process and a particularly satisfactory way of achieving this is electrically to copper-plate the surface of the nickel plate in the vicinity of the join. Afterwards the copper is removed by a reverse process.

An assembly of a pair of plates will now be described with reference to FIGURES 2 to 5. A printing cylinder 7 is transversely grooved at its periphery to form a substantially T shaped slot as shown at 8 in FIGURE 2 that is adapted to receive a clamping element 9 shown in FIGURES 2 and and a sole plate 10, shown in FIG- URES 2 and 4. The bar 9 is provided with an inverted T shaped longitudinal groove 11, a series of vertical clearances 12 and associated internal wedge surfaces 13. The plate is provided with a series of openings 14 to correspond with the wedges and also includes screws 25 for securing the bar 9 and the plate 10 in the slot 8 formed in the cylinder. The outer face 15 of the slot 8 are arranged to diverge slightly to correspond with the faces 5 of the clamping bars 2. The sole plate 10 must be of the correct thickness to ensure that the working surfaces of the printing plates assume a true radius in accordance with the cylinder 7. It should be noted that a clearance is provided between the clamping bars 2 and the faces 15 of the slot 8 to allow for adjustment. When the sole plate 10 and the element 9 have been secured to the cylinder, as by the screws 25, there will be provided in the cylinder and at its periphery a transverse groove comprising a groove portion in the cylinder itself housing the clamping bars 2 and the T-shaped groove portion 11 in the element 9.

The plates 10 and clamping elements 9 are secured to the cylinder through the medium of I section locking bar members, one of which is shown at 16. The upper portion of each locking bar 16 is arranged to engage in the transverse groove 4 formed in the associated clamping bar 2 and the lower portion of each locking bar is cut away at 18 to provide a series of downwardly directed projections 19 that are capable of passing through the openings 14 of the sole plate 10 and the vertical clearances 12 of the clamping bar 9 into the longitudinal groove 11. The upper faces 29 of the said downwardly directed projections 19 are tapered at an angle to provide wedge surfaces corresponding with the wedge surfaces 13 formed in the clamping slide. After the plates have been positioned, an axial movement of the locking bar will cause the respective wedge surfaces 13, to engage with one another so as to exert a downward force on the top of the locking bar so that the lower edges of the top part of the I section are wedged against the bottoms of the grooves 4 in the clamping bars 2, with the result that the plates 1 will be firmly secured to the cylinder. A pair of oppositely disposed set screws and associated locking nuts, shown diagrammatically at 21, FIG- URE 3, are provided to retain the locking bars 16 in their operative position and also to provide a lateral location of the clamping bars 2. The screws 21 are mounted within tapped plates 22 secured to the end faces of the printing cylinder.

Circumferential adjustment of the plates is provided by means of a series of grub screws 17 located within the tapped holes 6 of the clamping bars 2 and arranged to contact the respective inclined wall faces 15 of the slots in the cylinder. The grub screws may be pre-set by means of a suitable jig before the plates are fitted to the cylinder.

To facilitate the assembly of the plates, clamping devices may be temporarily used to provide tension. Finally, after assembly the resulting gaps between the plate sections are filled by means of a resinous or other material to provide an unbroken surface of the plate cylinder.

What is claimed is:

1. A printing cylinder assembly comprising a cylinder having a transverse groove at its periphery; a plurality of spaced transverse first wedge surfaces within said groove; printing plate means applied to the periphery of said cylinder and having ends contiguous to one another at said groove; transverse clamping bars affixed respectively to the undersides of said ends and being disposed in said groove; and a locking member connected to said clamping bars and being mounted to slide transversely in said groove, said locking member having a plurality of spaced second wedge surfaces complementary to and engaging said first wedge surfaces, whereby sliding of said locking member will cause an inwardly radial force to be imposed on said clamping bars through the coaction of said first and second wedge surfaces.

2. A printing cylinder assembly as claimed in claim 1 in which there is a first gap between said plate contiguous ends, and in which there are other gaps between adjacent clamping bars and between the clamping bars and the cylinder, said other gaps being so arranged as to occur below said first gap.

3. A printing cylinder assembly as claimed in claim 1 in which said printing plate ends have areas which have no effective printing surfaces, and in which there are gaps between adjacent clamping bars and between the clamping bars and the cylinder, said gaps being so arranged as to occur below said printing plate areas which have no effective printing surface.

4. A printing cylinder assembly as claimed in claim 1 in which the clamping bars are provided with adjustment means engaging walls of said transverse groove to enable the plate to be adjusted, tensioned and aligned.

5. A printing cylinder assembly as claimed in claim 1 in which the transverse groove in the printing cylinder is in the form of a substantially T shaped slot and said clamping bars have transverse grooves, and wherein there is a clamping element in said slot having an inverted T shaped groove, said locking member being of I section the upper portion of which engages in said transverse grooves in said clamping bars, the other end of said locking member being disposed in the head of the inverted T shaped groove in said clamping element.

References Cited in the file of this patent UNITED STATES PATENTS 1,049,195 Banzett Dec. 31, 1912 FOREIGN PATENTS 270/31 Australia Dec. 24, 1931 UNITED STATES PATENT OFFICE CERTIFICATE OF CORREQTION Patent No. 3 152, 544 Dated October 13, 1964 Inventor( Pete Henry Newman It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

The heading of the sheet of drawing containing Figure l and Figure 2 should include -2 sheets sheet l-.

A second sheet of drawing (see attached) "sheet 2", containing Figures 3-5, should have been included in the printed patent as issued.

Signed and sealed this-l9thday of September 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOI'TSCHALK Attesting Officer Commissioner of Patents FORM PO-1050 (10-69) USCOMM-DC 60376-P69 a u.s. sovznumsm' PRINTING omc: was o-ase-aan Oct. 13, 1964 3, 152,, 544

P, H. NEWMAN MEANS FOR MOUNTING PRINTING PLATES 3 Eiled Aug 5, 1963 2 Sheets-Sheet 2 W.- fiZu 19W man 

1. A PRINTING CYLINDER ASSEMBLY COMPRISING A CYLINDER HAVING A TRANSVERSE GROOVE AT ITS PERIPHERY; A PLURALITY OF SPACED TRANSVERSE FIRST WEDGE SURFACES WITHIN SAID GROOVE; PRINTING PLATE MEANS APPLIED TO THE PERIPHERY OF SAID CYLINDER AND HAVING ENDS CONTIGUOUS TO ONE ANOTHER AT SAID GROOVE; TRANSVERSE CLAMPING BARS AFFIXED RESPECTIVELY TO THE UNDERSIDES OF SAID ENDS AND BEING DISPOSED IN SAID GROOVE; AND A LOCKING MEMBER CONNECTED TO SAID CLAMPING BARS AND BEING MOUNTED TO SLIDE TRANSVERSELY IN SAID 